CN111247479B

CN111247479B - Curved display and sensor device

Info

Publication number: CN111247479B
Application number: CN201880068139.6A
Authority: CN
Inventors: W·H·里维斯
Original assignee: Fleck Innabur Technology Co ltd
Current assignee: Fleck Innabur Technology Co ltd
Priority date: 2017-10-20
Filing date: 2018-10-18
Publication date: 2023-11-14
Anticipated expiration: 2038-10-18
Also published as: GB2567679A; WO2019077061A1; US20200341323A1; CN111247479A; US11448912B2; GB201717278D0; GB2567679B

Abstract

A manufacturing process for forming a flexible assembly suitable for a bending sensor or display comprising a stack of layers defining an electrical control circuit is presented. The flexible assembly has a curved configuration and comprises at least a first component (4) and a second component (8) laminated together in a stressed configuration due to their curvature. Cutting at least the first component (4) and the second component (8) to obtain one or more edges aligned with each other when the assembly is in the curved configuration.

Description

Curved display and sensor device

Bending devices, such as bending displays and/or sensor devices, are of increasing interest. The display and sensor device comprises a layer stack defining an electrical control circuit, such as an active matrix control circuit, and the technique used to construct this layer stack on a flexible plastic support film provides the possibility to form the display and sensor device with a curved configuration.

Creating a bending device may include laminating flexible components together, and the inventors of the present application have worked on improving the mechanical stability of the bending device created in this way.

There is thus provided a method comprising: forming a flexible assembly comprising a layer stack defining an electrical control circuit for a sensor or display, wherein the flexible assembly has a curved configuration and includes at least a first component and a second component laminated together in a stressed configuration; and cutting through at least the at least first and second components to create one or more alignment edges in the at least first and second components when the assembly is in the curved configuration.

According to one embodiment, forming the assembly includes laminating the first component to a third flexible component in a curved configuration, and then laminating the second component to the first component in situ on the third component.

According to one embodiment, forming the assembly includes laminating the first component to the second component and laminating the first component to a third component in a curved configuration, wherein the second component is laminated to the first component.

According to an embodiment, the cutting comprises also cutting through the third component.

According to one embodiment, the third component comprises a flexible window/cover component.

According to one embodiment, the assembly comprises a liquid crystal cell interposed between two orthogonal polarizer films.

According to one embodiment, the first and second components comprise two encapsulation films, the liquid crystal cell and polarizer film being interposed between the encapsulation films, and wherein the cutting comprises cutting through at least the two encapsulation films and the window/cover component to create an alignment edge in at least the two encapsulation films and the window/cover component.

Embodiments of the application are described below, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 illustrates a bending assembly for a display device prior to cutting in accordance with an embodiment of the present application;

FIG. 2 illustrates the bending assembly of FIG. 1 after cutting in accordance with an embodiment of the present application; and is also provided with

Fig. 3 illustrates an example of a light modulator for the techniques of fig. 1 and 2.

Embodiments of the present application are described below with respect to examples of Liquid Crystal Display (LCD) devices, rather than touch sensors, but the same kind of technology is also applicable to LCD devices, including touch sensors, other types of display devices with or without touch sensors, and sensor devices (e.g., light/radiation sensors, etc.) with or without any display function, for example.

Embodiments of the application are described below with respect to examples of cutting through window/cover components and flexible encapsulation films in a curved stressed configuration, but the same kinds of techniques are also applicable to other flexible stressed components that additionally cut through a curved assembly, or cut through other flexible stressed components without cutting through a flexible encapsulation film, or cut through stressed flexible components in an assembly that does not include a flexible encapsulation film.

The example of fig. 1 involves laminating (sequentially or in combination) a plurality of flexible plastic film assemblies to a curved window/cover assembly 2 that forms an external screen in the finished display/sensor device. The plastic film assemblies each include at least one plastic film. The at least one plastic film may itself be a functional element and/or may support one or more functional elements.

The curved window/cover assembly 2 may, for example, comprise a flexible plastic support film that, in this embodiment, adopts a curved resting configuration in the absence of any applied external mechanical force, and tends to return to the curved resting configuration when flexed away from the resting configuration. Such window/covering assembly 2 may be produced, for example, by applying one or more desired coatings (e.g., scratch-resistant coatings, anti-glare coatings, etc.) to a flexible plastic film in a flat leaning configuration, and then molding the plastic film into the desired new curved leaning configuration by, for example, thermoforming techniques. When the window/cover assembly 2 is forced to flex away from its curved, new resting configuration, internal stresses are created within the window/cover assembly that serve to return the window/cover assembly to its curved resting configuration. Another example of a technique for creating a plastic window/cover assembly 2 with a curved resting configuration involves joining one surface area of a first plastic film subassembly (e.g., a hard coated planar acrylic sheet) to a smaller surface area of a second plastic film subassembly (e.g., another hard coated planar acrylic sheet of the same thickness), particularly by flexing one of the plastic film subassemblies into a stressed curved configuration, for example, using a lamination aid, and joining the other of the plastic film subassemblies to the one plastic film subassembly in place on the lamination aid. This alternative technique further facilitates the creation of curved window/cover assemblies with hard coatings without the need to coat curved surfaces.

In the example of fig. 1, the window/cover assembly 2 is supported on a curved surface of a rigid carrier (not shown) during the lamination process. The flexible plastic film assembly laminated directly or indirectly to the curved window/cover assembly 2 so supported in a stressed curved configuration comprises: a flexible encapsulation film 4 that acts as a barrier to prevent ingress of one or more damaging air substances (e.g., moisture, oxygen, etc.) through the plastic window/cover assembly 2; a flexible module 6 comprising two flexible orthogonal linear polarizer films laminated on opposite sides of the liquid crystal cell; and a second flexible encapsulating film 8 which also acts as a barrier against the ingress of one or more damaging air substances.

The liquid crystal cell comprises a thickness of liquid crystal material sandwiched between two flexible support films secured together by an adhesive, each of the two flexible support films supporting at least one alignment layer (e.g. a rubbed organic polymer layer, such as a rubbed polyimide layer) for controlling the state of the liquid crystal material together (with respect to how the liquid crystal material rotates the polarization of light) in the absence of an electric field generated electrically within the liquid crystal material. In this example, the LCD device is an Organic Liquid Crystal Display (OLCD) device that includes an organic transistor device (e.g., an Organic Thin Film Transistor (OTFT) device) for controlling the components. OTFTs include organic semiconductors (e.g., organic polymers or small molecule semiconductors) for the semiconductor channels. At least one of the two flexible support films sandwiching the liquid crystal material also supports a layer stack (e.g., comprising a metal layer, an organic insulating layer, and one or more organic polymer semiconductor layers) that defines an electrical control circuit (e.g., an active matrix circuit) for electrically controlling the state of the liquid crystal material in each pixel region (with respect to how the liquid crystal material rotates the polarization of light).

In this example, the flexible module 6 comprises a set of three pre-prepared plastic film subassemblies: a lower polarization filter assembly 132; a liquid crystal cell incorporating an electrical control circuit and a color filter array and pre-bonded to a Chip On Film (COF) unit; and an upper polarization filter assembly 130. In this example, all three subassemblies are prepared in a respective substantially planar resting configuration and joined together in their planar resting configuration, and the joined assembly is then joined to the curved window/covering assembly 2. According to a variant, the individual plastic film subassemblies prepared are joined together in situ on the curved window/cover assembly 2. In more detail, each plastic film subassembly of the set of subassemblies is sequentially joined to the curved window/cover assembly 2 via any of the plastic film subassemblies that have been joined to the curved window/cover assembly 2. Each bond may be achieved, for example, by a dry bond lamination technique.

An example of a flexible module 6, 42 is schematically illustrated in fig. 3. The stack 114 of conductor, semiconductor and insulator layers is formed in situ on a plastic support film 116. The stack 114 defines an array of pixel electrodes 118 and circuitry for independently controlling each pixel electrode via conductors external to the array of pixel electrodes 118. The stack 114 may, for example, define an active matrix array of thin film transistors, including: a gate conductor array, each gate conductor providing a gate electrode for a respective row of TFTs and extending outside the pixel electrode array; and an array of source conductors, each source conductor providing a source electrode for a respective column of TFTs and extending outside the array of pixel electrodes. Each pixel electrode is associated with a respective TFT and each TFT is associated with a unique combination of gate and source conductors, whereby each pixel electrode is addressable independently of all other pixels.

A substantially uniform thickness of liquid crystal material 120 is contained between the pixel electrode array 118 and a corresponding component 122 comprising a color filter array supported on another plastic support film. The COF unit 124 is bonded to a portion of the support film 116 outside the pixel electrode array 118 to establish a conductive connection between (i) an array of conductors (e.g., source and gate addressing conductors) defined by the stack 114 in a region outside the pixel electrode array 118 and (ii) a corresponding array of conductors of the COF unit that are connected to terminals of one or more driver chips 126, thereby forming part of the COF unit.

Each of the above-described flexible components (i.e., the encapsulation films 4, 8, polarizer films 130, 132, and liquid crystal cells) may be laminated to the window/cover component 2 (directly or indirectly), either individually or in combination with one or more of the other flexible components. In contrast to the window/covering assembly 2 in this embodiment, each flexible assembly laminated to the window/covering assembly has a flat resting configuration (each flexible assembly tends to adopt a substantially flat configuration in the absence of any mechanical external forces applied thereto). Each lamination involves taking a component or pre-laminated combination of components in a flat resting configuration to directly or indirectly laminate the component or combination of components to the curved window/covering component 2 in a deflected stressed configuration. The adhesive pre-applied to the surface of the component or combination of components and/or the surface to which the component or combination of components is laminated secures the component or combination of components to the curved window/covering component 2 in a flex-stressed configuration (directly or indirectly). The resulting assembly has a curved resting configuration, but each flexible component of the assembly is in a stressed configuration.

In this example embodiment, the encapsulating films 4, 8 are larger than the polarizers and LC cells of the module 6, and both extend beyond the edges of the module 6 on all sides.

In this embodiment, the second encapsulating film 8 is smaller in size than the first encapsulating film 4, such that in all edge regions of the first encapsulating film, the edges of the second encapsulating film 8 lie within the edges of the first encapsulating film 4. This smaller size of the second encapsulating film 8 facilitates deposition of an edge sealing material (not shown) to extend to the location where cutting is to be performed by capillary action between the first and second encapsulating films, as discussed later. The adhesive used to secure the two encapsulating films 4, 8 together is limited to the area inward of the cut area to allow the sealant to occupy the cut area. After the edge sealant is cured in place between the two encapsulating films 4, 8, the edge sealant serves to protect the module 6 (including LC cell and polarizer) from the ingress of one or more damaging air substances through the junction between the encapsulating films 4, 8.

After all components 4, 6, 8 are secured to the curved window/cover component 2 in the flex stressed curved configuration by the adhesive layer, a cut is made through all window/cover components 2 and the encapsulating film 4, 8 (in the region where the edge sealant is located as described above). Cutting is performed in (at least) two opposite edge regions extending parallel to the curvature axis (as indicated by the dotted cut lines in fig. 1) to create aligned edges in the curved window/cover assembly 2 and the encapsulating films 4, 8, as shown in fig. 2. The cutting may be performed, for example, using a laser cutter. The creation of alignment edges in the laminate assemblies as a whole in (or very close to) the curved resting configuration reduces the risk of the stressed laminate assemblies delaminating from one another, especially if the assemblies are later flexed out of their curved resting configuration.

After cutting, the assembly may then be mounted on a backlight unit, which may, for example, comprise a support structure having a curved outer surface defining a recess therein for receiving a backlight module comprising edge Light Emitting Diodes (LEDs) and a light guide plate to direct and distribute light from the edge LEDs output from an upper surface of the light guide plate substantially uniformly across the entire area of the light guide plate. If the backlight module has a flat resting configuration, the diffuser sheet may be fastened to the curved surface of the support structure to maintain the backlight module in a curved stressed configuration within the recess.

The curved outer surface of the backlight module may have a radius of curvature that is less than the radius of curvature of the assembly shown in fig. 2, and mounting the assembly of fig. 2 on the backlight module may involve flexing the assembly out of its curved resting configuration to some extent. As mentioned above, the techniques described above to create aligned edges in the window/cover component 2 and the encapsulating films 4, 8 will serve to reduce the risk of these components delaminating from each other as the assembly flexes away from its curved resting configuration.

In the above described embodiment, the window/cover assembly 2 has a curved resting configuration (due to, for example, thermoforming). According to one variation, the window/cover assembly 2 has a flat resting configuration and remains in a curved stressed configuration during the lamination process through the rigid carrier, mentioned above. After lamination is completed, all flexible components (including window/cover component 2) are held in a stressed bent configuration by the adhesive between each pair of flexible components.

According to another variation, the window/covering assembly 2 has a curved resting configuration and is sufficiently rigid to be laminated without the need for a rigid carrier to support the window/covering assembly 2.

The embodiment shown in fig. 1 and 2 involves cutting only at the outer edge of the assembly. However, according to one variation, the module 6 (polarizer+lc cell) may define one or more holes, and also cut through the window/cover assembly 2 and the encapsulating films 4, 8 in the region with the one or more holes to additionally create aligned inner edges in these three assemblies.

In addition to any of the modifications explicitly mentioned above, it will also be apparent to those skilled in the art that various other modifications may be made to the described embodiments within the scope of the application.

The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features. Such features or combinations can be implemented as a whole based on the present specification, regardless of whether such features or combinations of features solve any problems disclosed herein, as is common to those skilled in the art; and do not contribute to the scope of the claims. Applicant indicates that aspects of the present application may consist of any such individual feature or combination of features.

Claims

1. A method, comprising: forming a flexible assembly, the flexible assembly comprising: (i) A flexible module comprising a liquid crystal cell disposed between two polarizer films, and (ii) a first and a second encapsulation film, the flexible module being disposed between the first and second encapsulation films, wherein the flexible assembly has a curved configuration in which the flexible module and the first and second encapsulation films are laminated together in a stressed configuration; and cutting through at least the first and second encapsulation films to create one or more alignment edges in the first and second encapsulation films when the flexible assembly is in the flexed configuration.

2. The method of claim 1, wherein forming the flexible assembly comprises: laminating the first encapsulation film to a window/cover assembly in a curved configuration, laminating the flexible module to the first encapsulation film on the window/cover assembly in situ, and laminating the second encapsulation film to the flexible module on the window/cover assembly and the first encapsulation film in situ.

3. The method of claim 1, wherein forming the flexible assembly comprises: laminating the flexible module with the first and second encapsulation films together, and laminating the flexible module with the first and second encapsulation films to a window/cover assembly in a curved configuration in a state in which the flexible module is laminated with the first and second encapsulation films together.

4. A method according to claim 2 or claim 3, wherein the cutting through comprises: the window/cover assembly is also cut through.

5. A method according to claim 2 or claim 3, wherein the window/cover assembly comprises a flexible window/cover assembly.

6. A method, comprising: forming a flexible assembly comprising a stack of layers defining an electrical control circuit for a sensor or display, wherein the flexible assembly has a curved configuration and comprises at least a first component and a second component laminated together in a stressed configuration; and cutting through at least the at least first and second components to create one or more alignment edges in the at least first and second components when the flexible assembly is in the flexed configuration; wherein prior to the cutting through, the second component has a smaller dimension than the first component such that an outer edge of the second component is inboard of an outer edge of the first component.

7. A method, comprising: forming a flexible assembly comprising a stack of layers defining an electrical control circuit for a sensor or display, wherein the flexible assembly has a curved configuration and comprises at least a first component and a second component laminated together in a stressed configuration; and cutting through at least the at least first and second components to create one or more alignment edges in the at least first and second components when the flexible assembly is in the flexed configuration; wherein the flexible assembly comprises an edge sealant material at one or more regions between the first component and the second component, and wherein the cutting through comprises cutting at the one or more regions.

8. A method, comprising: forming a flexible assembly comprising a stack of layers defining an electrical control circuit for a sensor or display, wherein the flexible assembly has a curved configuration and comprises at least a first component and a second component laminated together in a stressed configuration; and cutting through at least the at least first and second components to create one or more alignment edges in the at least first and second components when the flexible assembly is in the curved configuration, wherein the cutting through is performed in one or more cutting areas; and wherein the flexible assembly includes an adhesive between the first component and the second component to secure the first component and the second component together, and wherein the adhesive is limited to an area inboard of the one or more cut areas.